snafu 0.4.4

An ergonomic error handling library
Documentation 
extern crate snafu;

use snafu::{Backtrace, OptionExt, Snafu};
use std::collections::HashMap;

#[derive(Debug, Snafu)]
enum Error {
    #[snafu(display = r#"("The left-hand argument {} was missing", "id")"#)]
    LeftHandMissing { id: i32, backtrace: Backtrace },
    #[snafu(display = r#"("The right-hand argument {} was missing", "id")"#)]
    RightHandMissing { id: i32, backtrace: Backtrace },
}

type Result<T, E = Error> = std::result::Result<T, E>;

fn example(values: &HashMap<i32, i32>, left: i32, right: i32) -> Result<i32> {
    let l = values.get(&left).context(LeftHandMissing { id: left })?;
    let r = values.get(&right).context(RightHandMissing { id: right })?;

    Ok(l + r)
}

#[test]
fn implements_error() {
    fn check<T: std::error::Error>() {}
    check::<Error>();
    example(&Default::default(), 1, 2).unwrap_err();
}